Method and apparatus for pumping oil wells in an underwater location



D. c. KOFAHL 2,935,024 METHOD AND APPARATUS FOR PUMPING on. WELLS IN AN UNDERWATER LOCATION 2 Sheets-Sheet 1 May 3, 1960 Flled Nov 5 1956 INVENTOR.

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1 Arroemers May 3, 1 960 D c KOFAHL 2,935,024

METHOD AND APPAATiJS FOR PUMPING OIL. WELLS IN AN UNDERWATER LOCATION Filed Nov. 5, 1956 2 Sheets-Sheet 2 INVENTOR DAVID C. KOFAHL ATTORNEYS METHOD AND APPARATUS FOR PUMPING OIL WELLS AN UNDERWATER LOCATION David C. Kofahl, Los Angeles, Calif., assignor to Richfield Oil Corporation, Los Angeles, Calif., a corporation of Delaware This invention relates to the pumping of oil wells which are positioned in an underwater location, for example, an offshore marine installation.

Where offshore wells have been drilled in relatively deep water from structures resting on bottom or from artificial islands the pumping apparatus may be located upon such structures or such islands after the drilling of the wells has been completed. However, when a well has been drilled from a floating barge or ship, the well head structure is positioned on the ocean floor and there is no platform or other support above water level upon which conventional pumping equipment may be mounted.

In accordance with this invention, a submerged buoyant 1 member is fixed to the sucker rod string which extends down through the eduction tube to the pump in the well. By alternately introducing sea water into the interior of the buoyant member and then expelling the sea water by use of gas under pressure obtained from the well, the effective buoyancy of the member is changed so that it is caused to reciprocate the sucker rod string and thus cause the pump to raise well fluid through the eduction tube. The well fluid passes through the well head structure and out through a submerged fluid delivery conduit.

In the drawings, Figure 1 shows a preferred embodiment of this invention in side elevation. Figure 2 is a sectional view showing typical connections of the valves to the submerged buoyant member.

Referring to the drawing, the well head generally designated 10 is mounted in a submerged location adjacent the ocean floor 11. Casing 12 extends from the well head 10 down into the well 13 and the interior of the casing communicates with the flexible hose 14 via the valve 15. An eduction tube 16 is supported by the well head 10 and extends downward into the well inside the casing 12. A conventional pump 17 is located in the lower end of the eduction tube 16 and this pump is driven by the reciprocating rod 18. The rod 18 extends completely through the well head structure and passes through the stufling box 19 at the upper end thereof. The interior of the eduction tube 16 communicates with the Well fluid delivery hose 20 via the valve 21.

A submerged buoyant member 22 which may be conveniently formed in the shape of a sphere is connected to the upper end of the rod 18 by means of the connection fittings 23. A pipe 24 is fixed within the interior of the buoyant member 22 and the upper end 25 of this pipe is open. The lower end of the pipe is fixed to the member 22 and communicates through the pressure sensitive valve 26 with the hose 14. Another pressure sensitive valve 27 is mounted on the buoyant member 22 and communicates with the interior thereof. The normally open pressure sensitive valve 27 may be similar to that shown in the Thomas Patent No. 2,013,222, dated September 3, 1935. The normally closed pressure sensitive valve'26 may be of the same general construction but provided with valve elements which close in the opposite direction, as shown in the Goehring Patent No. 2,110,859, dated March 15, 1938. Connections of these valves to the submerged United States Patent 2,935,024 Patented May 3, 1960 buoyant member 22 are shown in Figure 2. A normally open valve 28 communicates with the interior of the member 22. Valve 27 is mounted at a relatively high elevation of the member 22 and the valve 28 is mounted at a relatively low elevation thereon.

The member 22 remains submerged at all times. When the member 22 is at the lower end of its stroke a pressure sensitive valve 26 opens and the pressure sensitive valve 27 remains closed. Gas under pressure derived from the well 13 flows through the hose 14, valve 26 and pipe 24 and into the interior of the buoyant member 22. The pressure of the gas displaces sea water within the member 22 and causes the sea water to be discharged through the normally open valve 28. The member 22 becomes more buoyant and moves upward to the upper end of its stroke. The upward movement of the member 22 within the sea water changes the static head of pressure on the valves 26 and 27. When the change in pressure reaches a predetermined value the valve 26 closes and the valve 27 opens. Sea water enters the interior of the buoyant member 22 through the open valve 28, the gas escaping through the valve 27 which is now open. The member 22 becomes less buoyant and it moves downward after predetermined travel, increase in pressure of the water closes valve 27 and opens valve 26. The cycle of operations continues so long as gas under pressure is supplied through the hose 14. a

Reciprocation of the rod 18 via the buoyant member 22 causes the pump to raise well fluid through the eduction tube 16 and out through the valve 21 and fluid delivery hose 20.

The valve 28 may be closed whenever it is desired to shut down the well pumping operation.

While I have shown one form of apparatus for carrying out the method of my invention it will be understood that the invention may be performed using other types of apparatus.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth, but my invention is of the full scope of the appended claims.

I claim:-

1. In an under water oil well pumping installation having an eduction tube extending into the well, a pump at the lower end thereof, a submerged well head connected to the eduction tube, a reciprocable rod extending through the eduction tube to drive the pump, and passage means in the well head communicating with the well outside said eduction tube, the improvement comprising: a submerged buoyant member connected to the rod, conduit means connecting the interior of the buoyant member with said passage means to deliver gas under pressure from the well, and means for alternately charging the buoyant member with water and gas under pressure to change the buoyancy of said member and cause it to reciprocate said rod.

2. In an under water oil well pumping installation having an eduction tube extending into the well, a pump at the lower end thereof, a submerged well head connected to the eduction tube, a reciprocable rod extending through the eduction tube to drive the pump, and passage means in the well head communicating with the well outside said eduction tube, the improvement comprising: a submerged buoyant member connected to the rod, conduit means connecting the interior of the buoyant member with said passage means to deliver gas under pressure from the well, and means for alternately introducing water into the member to cause it to descend, and then introducing gas from said conduit means into the member to expel water therefrom to cause it to rise.

3. In an under water oil Well pumping installation having an eduction tube extending into the well, a pump at the l e ndv her f a submer ed wellhead c nn t d. to the eduction tube, a reciprocable rod extending through the eduction tube to drive the pump, and passag an well e qqmmuni ins w th h el outside said eduction tube, the improvement comprising a submerged buoyant member connected to the rod, conduit means connecting the interior ot the buoyant member with said passage means to deliver gas under pressure from the well, a pressure-sensitive valve in; said conduit and communicating with the water outside said member, said valve acting to close the conduit when the water pressure reaches a predetermined minimum, a second pressure-sensitive valve mounted on said member and adapted to establish open communication between the inside and outside of said member when the water pressure outside said member reaches a predetermined maximum, and passage means for admitting and discharging water from the interior of said member. 7

4. Pumping apparatus for a well in an oflfshore marine location, comprising in combination: an eduction tube extending into the well and having a pump at the lower end thereof, a submerged well head connected to the eduction tube and including a stuffing box, a reciprocable rod extending through the stufling box and through the eduction tube to drive the pump, a fluid-delivery conduit connected to the well head in communication with the eduction tube, passage means in the well head come municating with the well outside said eduction tube, a submerged buoyant member connected to the rod above the stutfing box, conduit means connecting the interior of the buoyant member with said passage means to deliver gas under pressure from the well, and means for alternately charging the buoyant member with sea water and then gas under pressure from the Well to change the buoyancy of said member cyclically and cause it to reciprocate said rod.

5. In an underwater oil well pumping installation having an eduction tube extending into the well, a pump at the lower end thereof, a submerged well head connected to the eduction tube, a reciprocable rod. extending through the eduction tube to drive the pump, and passage means in the well head communicating with the well outside said eduction tube, the improvement comprising: a submerged buoyant member connected to the rod, means connected with said passage means to deliver gas under pressure from the well to the interior of the buoyant member, said means including a pressure sensitive valve device adapted to open when waterpressure outside said member reaches a predetermined maximum, and means to discharge gas and admit water into the interior of said member when the water pressure outside said member reaches a predetermined maximum whereby the cyclical change in buoyancy of said member causes it to reciprocate said rod.

Vinson Sept. 6, 1938 Levin Jan. 9, 1951 

